Detectives are warning residents to be on their guard against a postal scam on Teesside.

The alarm was sounded by Cleveland Police after scores of Middlesbrough residents received an official-looking note through their doors.

Pensioner Doreen Stockton received a card saying a parcel could not be delivered to her because of under-paid post.

It advised her the item would be delivered for a fee of #4.60, to be sent to a PO box address in Middlesbrough.

Mrs Stockton, of Mandale Road, Acklam, said: "It is very amateur looking. It shouts scam at me. Somebody is asking for money for nothing.

"It just concerned me that somebody might send the money off," she added.

One resident of Heythrop Drive who received the note attempted to check the details of the company and postal address given on the form but could not find them on the internet, so he called the police.

The man, who did not want to be named, said: "When I looked out, I saw a gentleman walking along Heythrop Drive randomly putting cards in some letterboxes."

Det Sgt Dino Carlucci, from the economic crime unit, said: "Although we have traced a large number of recipients, we are concerned that many people could still be ripped off.

"This is a clever scam which preys on people's curiosity without trying to generate large amounts of money from an individual.

"If you consider that hundreds of letters may have gone out, even if a small percentage reply it nets the thief a decent windfall.

"It's a large amount of money for little effort, but we want to ensure it is stamped on and more people aren't caught out.

"My advice is if you have one of these notes and haven't done anything with it, just destroy it.

"However, if you have already sent off the money, please forward the note, along with your details, to DC Andy King at the economic crime unit at Coulby Newham Police Station, Bickley Way, Coulby Newham."

A 44-year-old man has been arrested and is currently on bail pending further inquiries.